Buttonless holder

There are a lot of duvet clips on the market but all leave a hard piece of plastic outside - this is covered by the sheet and hidden.

1.  First You align the sheets 
2.  Put the rectangular ring on top
3.  Push&rotate the crescent disc from below through, with the opening engaging the ring
4.  Now turn flat an pull the surplus tissue and it is locked.

To open you first have to create a pocket by pulling the disc while holding the ring down so you have enough space to turn the disc vertical and with the opening registering the ring.

For a temporary fast connection you can also just use a coin or washer

Also can make a pocket into a towel to hang. Or a keyring holder on your t-shirt. Maybe you need to span a sunshade. Or this comes in handy when building a blanket fort.